The arrest of a Southern California man has done little to explain a mysterious triple-slaying involving two brothers and one sibling’s fiancée.

Carlo Gallopa Mercado, 29, was arrested Friday and booked on suspicion of killing Salvadore Belvedere and Ilona Flint, both 22, in the early hours of Christmas Eve last year. Both were shot in a mall parking lot.

The shooting has perplexed investigators from the beginning, with no apparent motives. The mystery deepened further when Flint’s fiancé, Gianni Belvedere, 24, appeared to have gone missing.

He was found dead weeks later, his body in a car trunk in a town 100 miles north. Mercado is also suspected of killing Gianni Belvedere.

The slayings shook the local community and baffled police.

Now Mercado, who worked for Target, is suspected of being involved, police say. Little is known about him, other than his pleading guilty to a felony charge of possessing a silencer in April. Additionally, police aren’t saying what evidence they have against Mercado, or how they found him.

Mercado’s family released a statement expressing their sadness over the deaths.

“On behalf of Carlo Mercado, we would like the community to know how sorry we are for any pain the Flint and Belvedere families have suffered and are suffering,” the statement reads.

“We have only had limited contact with Carlo since his arrest and have not been made aware of any evidence against him. We remain fully supportive of him and ask the public to respect our privacy during this difficult time.”

For relatives of the victims, news of the arrest provided some semblance of closure.

“It’s a sense of relief to get this information that someone’s been caught,” said Antoinette Belvedere, sister of the victims.